Table 3.

Friction force and shear stress for all pads of male and female beetles

Male Female
FrictionPad:DistalMiddleProximalDistalMiddleProximal
Smooth surfacePullForce (mN)15.54±2.108.50±1.3833.55±2.4215.60±2.265.52±0.8514.76±2.35
(N=5)Stress (kPa)642±991088±2191093±68613±111761±150747±114
PushForce (mN)2.58±0.251.18±0.169.51±0.851.84±0.340.95±0.212.84±0.48
(N=5)Stress (kPa)203±18535±172585±92144±38413±162589±177
Rough surfacePullForce (mN)3.80±0.520.90±0.121.08±0.134.29±0.350.99±0.111.38±0.12
(N=5)Stress (kPa)143±21105±1436±4157±13122±1468±6
PushForce (mN)0.43±0.070.24±0.040.29±0.040.37±0.060.22±0.020.39±0.08
(N=5)Stress (kPa)26±457±1014±221±362±646±9
  • Values are mean ± s.e.m. On the rough surface, contact area could not be measured therefore shear stress was calculated using the mean maximal setal contact area of the same pad on glass